September 2012 Chevy High Performance Q&A - It Has Come In Twos

It Has Come In Twos

The past month has had a consistent theme. I lost two very close races by a couple of thousandths. Both of them were my fault, mind you; I had both the races won. This sport of drag racing will humble you down every time you think you’ve got it figured out. Unfortunately, one of the races was an NHRA National event where I had qualified number one, and had the best package of the event (0.006) second round (see the theme), only to give up the stripe in the third round by 0.002 second! The second race was one of our Summit ET series points races, which I promptly lost in the second round by a couple of thousandths by breaking out by more than my opponent had. If I keep racing like this I better find a new hobby. Then again, maybe someone has made that decision for us.

The second blow to motorsports came with the announcement of the closure of Toyota Irwindale Speedway. This was one of the country’s premier short tracks. Every year you could watch the NASCAR Toyota All-Star Showdown. This race was televised on Speed, featuring the NASCAR K&N Pro Series, where teams from the East and West series battle it out for national bragging rights. Not only did we lose this very nice facility for circle racing, there was also an eighth-mile dragstrip that hosted a weekly Thursday night program and a monthly Summit ET series event. Irwindale has been fielding a Summit team to the ET finals for the past 10 years.

To drive the final nail in the Los Angeles racing scene was the announcement of the closure of Auto Club Dragway Fontana. As I have written in the past, it’s time for us racers to be better neighbors. This (temporary) closure is the result of a multiyear litigation with local homeowners over noise issues at their homes. The judge on the case ruled that the previous Environmental Impact Report was not valid and required that the track close until a new study could be run with a sound wall in place. Not only does the new report have to be run, the track must meet much more stringent sound requirements than in the past. Last year we had a much-abbreviated season because of the legal battle. Now, we’ve lost the track for an unknown period. In my opinion, it will take at least a year to satisfy the judge, if we can at all. I pray that we see our track back in the future. With this closure, there are no active dragstrips in the L.A. area. With the price of fuel, it makes traveling almost out of the question.

As I said above, maybe someone made the decision for us to try our hand at some other motorsports activities for a while. Since our drag racing hardware has been parked, we may need to turn up the heat and finish our track day car. This will give Daniel and I a purpose-built track car that we can compete in local (Auto Club Speedway) road race events, autocross, drifting, and time-attack. Keep in touch and we’ll bring you up to speed on our small-block install and ’cage fabrication on a Brand-M sports car. Sounds like something to keep me out of trouble. Until next month, be safe!

Crate Debate

Q. I enjoy reading your Q&A every month. Could you help me decide which crate engine I should go with for my ’83 Z28? I want to choose between the ZZ4 and the ZZ383 GM crate engines. My car is carbureted with automatic, and I will be mating the new engine to a 700-R4 with either 3.42 or 3.73:1 gears. I know the ZZ4 is available turnkey with a carb, a distributor, and wires, and the ZZ383 needs an intake, a carb, a water pump, and more.

I have heard that the ZZ4 is somewhat mild and could use more cam timing. The ZZ383 comes with a higher lift, a greater-duration cam, and roller rockers, giving it 70 hp and 45 lb-ft more than the ZZ4.

I have owned my ’83 for 23 years, and all this time it has been powered by a 150hp LG4 (which is now very tired), so maybe the ZZ4’s extra 200 horses would work for me and make the car a decent performer. The car is a street car. I have put it down the quarter at 16.28 (best time). I would like the car to run at least low 14s or high 13s.

Gary Kilbride Goodwood, ON, Canada

A. The change in personality when you add 200 hp and a ton of torque to your dead original ’83 Z28 will surprise you. If you’ve read the column for any period of time you will know we have many years with the ZZ4 engine. Yes, the turnkey ZZ4 PN 19201330 is a very mild engine because of its dual-purpose design. It’s a great engine and will impress you on many levels. With peak torque coming at 405 lb-ft, it really moves you around.

Now, the ZZ383 PN 12498772 is nothing to sneeze at. The base short-block was stolen from the HT383, which is a very heavy-duty, purpose-built truck short-block. It’s packed with a 4340-forged steel crankshaft, swinging a 3.80-inch stroke combined with a standard 4.00-inch bore yielding 383 cid. Attached to this bulletproof crankshaft is a set of heavy-duty powdered metal rods measuring out at 5.7 inches long and rated up to 550 hp! Finally, filling the bores are a set of hypereutectic aluminum pistons, which give you great ring seal and quiet operation. Yes, the camshaft is quite a bit larger than the ZZ4, spec’d out at 222/230 degrees duration at 0.050-inch tappet lift, 0.509/0.528-inch max lift, and is ground on 112 centers. This is a great middle-of-the-road camshaft for a 383, not going too large for a fully accessorized Camaro with power steering, A/C, and an automatic transmission. Finally, topping off the short-block is a set of Fast Burn cylinder heads. The ports on these cylinder heads started life as the famed LT4 Corvette cylinder heads that were hand-ported and digitized to create the core boxes for these casting. This gives you an as-cast ported set of heads. Among the 33 inches, ported LT4 cylinder heads, and the larger camshaft is where you find the 70hp bump. For all these reasons we recommend this package for your application.

GM recommends its Vortec-designed single-plane intake manifold (PN 12496822). This is a good choice, but for an all-around great street package, we would top it with the Vortec-designed high-rise dual-plane (PN 12366573), which features a square-flange carburetor mount, and a hot water crossover to preheat the manifold in cold climates like Canada. The Fast Burn heads do not have an exhaust crossover, and therefore in cold climates lends itself to carburetor icing.

You didn’t state if you were going to park your Camaro over the winter. We fought with icing issues with the LT4 cylinder heads and it’s not fun. Be aware that you’ll lose around 15 peak horsepower with the dual-plane design; however, the gain in slow-speed torque and midrange will more than make up for the few ponies you lose upstairs.

To finish off your swap you can drop in a new HEI distributor (PN 93440806). We’re partial to a standard 4779 750 double-pumper Holley. These carburetors will drop right on your engine and perform out of the box. You can reuse all the front accessory drives from your ’83 Camaro. It will bolt right up for trouble-free service. Finally, you’ll need to use at least a set of shorty headers—or if you’re adventurous, we’d recommend a set of long-tube headers. Many would suggest 13/4-inch primary tube headers, but sticking with the torque theme of your engine, it would love a set of 15/8-inch primaries. Check out a set of Hedman Hedders (PN 68469). These feature 15/8-inch primaries, 3-inch collectors with three-bolt flanges, and have D-shaped exhaust port flanges to match your Fast Burn cylinder heads. You will need to complete the remaining dual-exhaust system with 21/2-inch tubing. It’s tough but it can be done. Check with a local muffler shop before you take this on.

This package will put your Camaro into the high 12-second e.t. range if you can get a hold of the track! We would stay with the 3.42 gears; the 383 will have plenty of slow-speed torque matched with your 700-R4 low First gear ratio. We hope we have answered all your burning crate debate questions. Let us know how it turns out!

Sources: gmperformanceparts.com,
hedman.com

Gearing for Torque or Horsepower

Q. If the torque of an engine moves a car, then why does everyone tell you to gear for the horsepower curve? Could you please explain the principles involved, and why? In case it makes a difference, I drag race and do land speed racing. I’m tempted to change to taller rear gears and use the torque band more. What do you think?

I love your column; it’s one of the reasons I subscribe to Chevy High.

Larry LancasterVia email

A. Horsepower is just a mathematical equation of torque and rpm. The higher you carry torque in engine speed, the more horsepower you make. As I corrected myself last month, the formula is torque multiplied by rpm divided by 5,252 equals horsepower. With that said, if you have 400 lb-ft at 5,000 rpm and 400 lb-ft at 7,000 rpm, you have much higher horsepower at the 7,000-rpm mark; 400 lb-ft at 5,000 rpm gives you 380.8 hp, and 400 lb-ft at 7,000 rpm produces 533.1 hp.

When someone says to gear for the horsepower curve, they are usually referring to where peak horsepower is, and where the engine drops into the torque curve on gear changes. If you have a wide powerband (and early torque peak and late horsepower peak), you have a very forgiving power curve. This type of power curve will pull vehicles around easily. When you have a narrow powerband, you need to keep the engine “on the pipe”, like a two-stroke motorcycle engine. This is why with high-strung engines you’ll usually find close-ratio manual gearboxes to keep the engine in its powerband.

Racing automatics with high stall-speed converters, you’ll usually want your full stall speed to be a couple of hundred rpm over torque peak. This is especially true when using Powerglide two-speed transmissions. When you launch the car with a Powerglide, the engine sits at stall for a period of time before the engine begins to accelerate. Then again, when you shift into high, the engine falls back into the stall of the converter and must accelerate away again. If the full stall speed is below torque peak, it can be difficult for the engine to accelerate through torque peak.

When you say that you drag and land speed race your car, there is probably nothing farther apart, as for setup. A good friend, Tim Moore, used to do both with his ’67 Camaro. It had a nasty little 350 small-block and a Super T10 trans. When he would drag race, we would swap out the 9-inch third member with 5.43 rear gears and a spool. When he took the car to the dry lakes, we would swap out for a 3.25 third member and a posi. In either application it would go through the traps at 7,000 rpm. At the dragstrip it was going 118 mph, and on the lakebed, in the flying mile, it ran 164 mph. Again, we geared the car to reach horsepower peak at the finish line. This is an example of where it was tuned for the horsepower curve. The toughest gear change was from Third to Fourth on the lakebed. The Super T10 was a close-ratio gearbox, and the little Mouse would just barely pull away from the gear change.

The point is there won’t be one gearset that will be optimal for both land speed competition and drag racing. Either pick one type of racing or prepare yourself to get your hands dirty between events. Hope this has helped. Have fun! CHP

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